Exploring, drilling, and completing hydrocarbon wells are generally complicated, time consuming, and ultimately very expensive endeavors. As a result, over the years, well architecture has become more sophisticated where appropriate in order to help enhance access to underground hydrocarbon reserves. For example, as opposed to wells of limited depth, it is not uncommon to find offshore and certain other hydrocarbon wells exceeding 30,000 feet in depth. Furthermore, today's hydrocarbon wells often include deviated or horizontal sections aimed at targeting particular underground reserves. Indeed, at targeted formation locations, it is quite common for a host of lateral legs and perforations to stem from the main wellbore of the well toward a hydrocarbon reservoir into the surrounding formation.
The above described perforations are formed and effectively completed by a series of applications that begin with perforating the wellbore. So, for example, a casing defining the well may be perforated with use of a perforating gun. The gun itself may include a cylindrical carrier of stainless steel or other suitable material that houses a carrier tube equipped with conventional shaped charges. Thus, the shaped charges will be detonated with explosive forces therefrom directed out of the gun and toward the well wall and/or casing in order to form the noted perforations.
In many circumstances, the described perforating application takes place in conjunction with the installation of completions hardware in mind. For example, lower and upper completions hardware may be installed in the well with a barrier valve or other form of well control maintained therebetween. Thus, a subsequent intervention in the form of the noted perforating may present challenges to maintaining well control.
With this in mind, efforts have been undertaken to prevent loss of well control by the introduction of a perforating gun into a well. For example, breaching a barrier valve to run a perforating gun into the well may not be required in circumstances where the gun itself is installed in conjunction with the completions hardware. Thus, rather than an intervention trip into the well for the sake of perforating, the gun may already be in place when the time for perforating arrives.
Unfortunately, installing completions or other isolation-type hardware already outfitted with a perforating gun, means that once the perforating application is completed, a gun immediately adjacent to newly formed perforations is left in place. Thus, production flow from the perforations may be obstructed to a degree by the gun and associated hardware.
Nevertheless, in order to prevent the perforating gun from remaining an obstacle to efficient production, the architecture of the well may include a “rat hole” or tail at its terminal end where the gun itself may be discarded. So, for example, during drilling of the well, an additional unused well space may be drilled to receive the gun. Following the perforating application, the gun may be cut off or released into the tail so as to no longer present an obstruction to production from the newly formed perforations.